3 day a week at home training program

Do you feel embarrassed to go to the gym or you don't have the time and money. Then this workout is made for you.
This workout is based on a 3 day a week workout program, the workouts should not take longer then 30-40 minutes. They do not require any equipment and can be done in the comfort of your own home. 
The workouts consists of 3 sections, a small warm up section, a core/abs section and either a circuit or a HIIT section.